Rewind starter

ABSTRACT

A rewind starter secured on the side of an internal combustion engine has a gear which is rotatable and axially slidable on a shaft which is rotatable in one direction by a pull cord wound on a pulley and in the opposite direction by a rewind spring. Means is provided for connecting the gear to the shaft so that when the shaft is rotated by pulling the cord, the gear is first moved axially to engage gear teeth on the fly wheel of the engine and then rotated with the shaft to crank the engine. When the engine starts, it immediately accelerates to a speed much higher than cranking speed. The starter gear is thereupon disengaged from the fly wheel gear but before full disengagement, it is given a forward spin. The connecting means between the starter shaft and gear permits the gear to overrun the shaft and avoids shock or impact. Means is provided for applying a frictional drag to rotation of the gear.

United States Patent 1 Sherwood et al.

11 3,783,851 Jan. 8, 1974 REWIND STARTER [73] Assignee: Textron, Inc., Providence, R.l.

[22] Filed: July 31, 1972 [21] Appl. No.: 276,536

[52] US. Cl. .t 123/185 BA, 74/7 R [51] Int. Cl. F02n 3/02 [58] Field of Search 123/185 R, 185 A,

123/185 BA, 185 B, 185 BB, 179 M; 74/7 R [56] References Cited ,UNITED STATES PATENTS 2,604,882 7/1952 Schnacke 123/185 BA 1,059,679 .4/1913 Lynnockm 123/185 BB Primary ExaminerLaurence M. Goodridge Assistant ExaminerDennis Toth -kTt taFrZy- Robert E. Burns em; V

[57] ABSTRACT A rewind starter'secured on the side of an internal combustion engine has a gear which is rotatable and axially slidable on a shaft which is rotatable in one direction by a pull cord wound on a pulley and in the opposite direction by a rewind spring. Means is provided for connecting the gear to the shaft so that when the shaft is rotated by pulling the cord, the gear is first moved axially to engage gear teeth on the fly wheel of the engine and then rotated with the shaft to crank the engine. When the engine starts, it immediately accelcrates to a speed much higher than cranking speed. The starter gear is thereupon disengaged from the fly wheel gear but before full disengagement, it is given a forward spin. The connecting means between the starter shaft and gear permits the gear to overrun the shaft and avoids shock or impact. Means is provided for applying a frictional drag to rotation of the gear.

C I aims, Drawing Figures I l up PAIENTEBJAN 1 M 3.783.851

SHEET 1 BF 2 PATENTED 3,783,851

SHEET 2 [IF 2 FIG. 3

FIG. 4

REWIND STARTER FIELD OF INVENTION The present invention relates to a starter for an internal combustion engine and particularly a manually operated rewind starter.

BACKGROUND or INVENTION A rewind starter comprises a rotatable driving member which is engageable with a driven part of the engine and is rotated by means of a pulley on which a pull cord is wound. When the cord is pulled by means of a handle provided on its outer end, the driving member is brought into engagement with a driven part of the engine so as to impart a cranking movement to the engine. A spring is provided for rotating the pulley in the composite direction in order to rewind the cord. When the enginestarts, it quickly accelerates a speed much higher than cranking speed with the result that unless the driving member of the starter can disengage itself from the engine immediately, it is driven by the engine. The resulting overrun of the driving member'may subject the winding mechanism to considerable stress resulting in ultimate failure of the starter.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved starter which is free of the disadvantages inherent in starters presently available. In particular, it is an object of the present invention to provide a starter in which the member driving the engine is free to overrun when the engine starts without causing any shock or stress either to the engine or to the starter.

In accordance with the present invention, the gear or other driving member of the starter is rotatable and axially movable on a shaft which is rotatable, for example by a pull cord wound on a pulley fixed to the shaft.

Means is provided for connecting the driving member to the shaft so as to move it axially into engagement with a driven part of the engine and then cause it to rotate with the shaft so as to crank the engine. When the engine starts and thereby attains a speed considerably higher than cranking speed, the driven member of the starter is disconnected from the shaft so as to free wheel without rotating the shaft. When the driving member has disengaged itself from the driven part of the engine and has decelerated, it is again connected to the shaft through the connecting means so as to be ready for'the next starting operation. By reason of the construction and operation in accordance with the present invention, the starter and the engine are relieved from shock incident to overrun of the driving member.

A further advantage of a preferred embodiment of the invention is that the starter is mounted at the side of the engine instead of at the end in alignment with the engine crank shaft. This provides a more rugged mount for the starter and moreover results in a substantial decrease in the overall length of the enging while providing for the convenient and reliable mounting of a fan or blower on the end of the crankshaft for cooling the engine. As the starter can be mounted on the same side of the engine as the carburetor or other engine accessories there is a substantial saving in space. Moreover, for

many installations, for example in snowmobiles, the starter is made more conveniently accessible. Still other features and advantages of the invention will appear from the following description.

BRIEF DESCRIPTION OF DRAWINGS A preferred embodiment of a rewind starter in accordance with the present invention is shown by way of example in the following drawings in which:

FIG. 1 is an end view of the starter shown mounted on an engine, aportion of which is-shown to illustrate the relation of the starter to the engine;

FIG. 2 is an axial sectiontaken approximately on the line 2-2 in FIG. 1; 1

FIG. 3 is a somewhat enlarged side view of a portion of the starter; and,

FIG. 4 is a section taken approximately on the line 44 in FIG. 3.

DESCRIPTION OF A PREFERRED EMBODIMENT A starter 1 in accordance with the present invention is shown in FIG. 1 as being mounted on the side of an engine 2 having a gear wheel 3 fixed on the engine crank shaft for example by providing gear teeth on the periphery of the flywheel. Referring particularly to FIG. 2, the starter is shown as comprising a housing 4 having a substantially cylindrical wall portion 4a and an intermediate transverse web portion 4b. The housing further comprises an end cover 5 which is removably secured to the cylindrical wall portion 4a, for example by bolts or screws 6.

A hollow shaft 7 is rotatably mounted in the housing 4 by means of central bearings in the transverse web portion 4b and in the cover 5. At opposite ends, the hollow shaft 7 is provided with symmetrical slots 7a and 7b respectively which, as seen in FIG. 2, extend through opposite sides of the shaft. The slots 7a are the same as the slots 7b and opposite ends of the shaft 7 are otherwise identical thus facilitating assembly of the shaft in the housing.

A pulley 8 provided on the shaft in the space between the transverse web portion 4b of the housing and the cover 5 has opposite side flanges 8a and 8b. A cord 9 wound on the pulley between the flanges 8a and 8b has one end secured to the pulley by a knot 9a while the opposite end portion of the cord extends out through a tangentially arranged exit portion 4c of the housing and is attached to a handle 10. The pulley 8 has an axially extending integral hub portion 8c on which a rewind spring 11 is spirally wound, one end of the spring being secured to the hub portion 8c and the other end beingsecured to a pin 12 extending inwardly of the cover 5. The cord 5 and the spring 11 are wound in such direction that the pulley 8 is turned in one direction by pulling on the cord 9 by means of the handle 10 thereby winding the spring 11 tighter and is turned in the'opposite direction by the spring so as to rewind the cord on the pulley. The pulley 8 is confined axially between the transverse web portion 4b of the housing and the cover 5 and is secured to the shaft 7 so as to rotate therewith by means of a transverse pin 13 which extends through the slots 7a of the shaft. A washer 14 retained by a snap ring 15 fitting in an annular groove on the shaft secures the shaft against moving axially toward the right as viewed in FIG. 2. I

On the opposite side of the transverse wall 4b of the housing, a gear 16 is mounted on the shaft 7 so as to be rotatable and axially slidable on the shaft. The gear comprises a hub 17 having a radially extending flange portion 17a to which the gear is secured by a plurality of machine screws 18. The hub 17 is provided with opposite spiral slots 17b (see FIG. 4) which are closed at one end and open at the opposite end onto the outer end face 170 of the hub. A spring 19 acting between the hub 17 and a washer 20 retained on the shaft 7 by a snap ring 21 fitting into an annular groove tends to move the hub 17 and thus the gear 16 inwardly toward the transverse wall 4b of the housing.

Means is provided for connecting the gear 16 with the shaft 7 so as to move the gear axially outwardly to bring it into engagement with the gear 3 of the engine and then cause it to rotate with the shaft to crank the engine upon rotation of the shaft 7 by pulling on the cord 9 wound on the pulley 8. The connecting means is shown in the drawings as comprising a plunger 22 which is slidable axially in the hollow shaft 7. A transverse pin 23 disposed diametrically of the plunger 22 extends out through the axial slots 7b of the shaft and into the spiral slots 17b of the gear hub 17. Engagement of the pin 23in the slots 7b prevent rotation of the plunger relative to the shaft. The plunger is biased inwardly toward the pulley 8 by means of a coil spring 24 disposed inside the hollow shaft and acting between the plunger and a cross bar portion of the washer 20 disposed in the slots 7b.

Means is provided for applying a drag or frictional resistance to rotation of the gear 16 so that the gear is shifted axially into engagement with the gear 3 of the engine before it is rotated by rotation of the shaft 7. Moreover, the drag means acts to decelerate the gear after the engine has started. In the illustrated embodiment, the drag means comprises an annular friction disc 25, a portion of which is captured between the gear 16 and a recessed annular portion of the flange 17a of the hub. Rotation of the friction disc 25 is prevented by radially projecting finger portions 25a which are received between axially extending inwardly projecting ribs 26 (FIGS. 1 and 2) on the inner surface of the housing 4. One or more spring pressed friction pads 27 recessed in the gear 16 bear on the friction disc to provide a selected drag on the gear.

The starter is removably mounted on the side of the engine 2 by means of tension bands 28 which pass around the housing of the starter and around arcuate anchorage portions 29 provided on the housing of the engine. Threaded tensioning devices 30 are provided for pulling the bands tight and thereby securely holding the starter on an arcuate seat 29a provided on the engine housing.

OPERATION During static condition the cord 9 is fully wound on the pulley 8 so that the handle is held against the exit portion 4c of the housing as seen in FIG. 1. The rewind spring 11 is partially unwound. The gear 16 is in the solid line position shown in FIG. 2 so that it is out of engagement with the gear 3 of the engine. The plunger 22 is biased to its inner position by the spring 24. When it is desired to start the engine, the cord 9 is pulled by means of the handle 10 and unwinds from the pulley 8 thus causing the pulley and hence the shaft 7 to rotate in a counterclockwise direction as seen in FIG. 1. By reason of engagement of the pin 23 in slots 7b of the shaft, the plunger rotates with the shaft. Outer end portions of the pin 23 engaged in the spiral slots 17b of the gear hub 17 exert a force on the hub having a component tending to move the hub and gear axially outwardly against the bias of the spring 19 and a component tending to rotate the gear in the same direction as the shaft 7. As the pin 23 is at the bottom of the slots 7b and as the drag imposed by the friction plate 25 resists rotation of the gear, the gear 16 first moves axially to the broken line position shown in FIG. 2 so as to engage the gear 3 of the engine. When the pin 23 reaches the blind ends of the spiral slots 17b of the gear hub, axial movement of the gear 16 is stopped and continued rotation of the shaft 7 thereupon rotates the gear 16 and hence the gear 3 to crank the engine. As the gear 16 is smaller than the gear 3, a speed reduction and mechanical advantage are provided.

When the engine starts, it quickly accelerates to a speed much greater than cranking speed. The driving gear 16 is thereupon moved toward the left as viewed in FIG. 2 by engagement of the helical slots 17b of the gear hub with the pin 23, which is held at the bottom of the slots 7b by the spring 24, so as to disengage the starter gear 16 from the engine gear 3. However, before the gear 16 is fully disengaged, it is given a sharp forward spin by the engine gear 3. It hence rotates faster than the shaft 7 which may moreover, have reached the end of its travel. When the gear 16 has moved .axially to the left to the position shown in solid lines in FIG. 2, continued forward rotation of the gear 16 causes the plunger 22 to be moved axially outwardly by engagement of the helical slots 17b of the gear hub with the pin 23 so that the pin is expelled from the open ends of the helical slots 17b and rides on the end face of the hub. This permits the gear 16 to overrun the shaft 7 until it has been decelerated and stopped by the braking action provided by the friction disc 25 so that no shock or undue stress is imparted to the starter mechanism. The spring 24 biases the plunger 22 toward the left as viewed in FIG. 2. If the gear stops with the pin 23 in alignment with the helical slots 17b, the pin enters the slots. Otherwise the pin 23 is pressed against the outer end face of the hub 17 by the spring 24 and enters the slots 17 when the shaft 7 is rotated at the beginning of the next starting operation. Upon release of the handle 10, the rewind spring 11 rotates the shaft 7 in the opposite direction so as to rewind the cord 9 on the pulley 8. The starter is thus reset for its next operation. While the engine is running, the driving gear 16 is held out of engagement with the engine gear 3 by the spring 19.

While a preferred embodiment of theinvention has been illustrated in the drawings and is herein particularly described, it will be understood that the invention is in no way limited to this embodiment.

What we claim and desire to secure by letters patent l. A starter for an internal combustion engine, comprising a housing, a shaft rotatable in the housing, means for rotating said shaft in a first direction to impart a starting movement to the engine, an engine driving member rotatable and axially slidable on said shaft and having a hub portion with a spiral slot opening onto one end face of the hub, a connecting member rotat able with and slidable axially of said shaft and having a projecting pin portion engaging in said spiral slot of said hub portion upon rotation of said shaft in said first direction to move said driving member axially into engagement with a driven means of said engine and thereupon to rotate said driving means in said first direction to impart a starting movement to the engine, said pin portion being engageable by said slot upon starting of the engine to drive said driving member faster than said shaft to move said connecting member axially to expel said pin portion from the open end of said slot and thereby disconnect said driving member from said shaft to permit overrun of said driving member, and means for biasing said connecting member axially in a direction opposite to said movement by overrun of said driving member.

2. A starter according to claim 1, in which said shaft is hollow with an axially extending slot in a portion thereof, and in which said connecting member comprises a plunger slidable in said shaft and a radially projecting pin portion extends out through said axial slot in the shaft and into said spiral slot in the hub portion of said driving member.

3. A starter according to claim 2, in which said hub portion and said shaft have two symmetrically opposite slots and said plunger has a transverse pin extending out through the two opposite axial slots in the hollow shaft into the two opposite spiral slots in the hub portion of said driving member.

4. A starter according to claim 3, in which said hollow shaft is symmetrical relative to a central transverse plane, with said opposite slots at one end to accommodate said pin and like opposite slots at the other end to accommodate means for connecting to said shaft said means for rotating the shaft.

5. A starter according to claim 2, in which said biasing means comprises a coil spring in said hollow shaft acting between said plunger and an anchorage fixed to said shaft.

6. A starter according to claim 5, further comprising a coil spring surrounding said shaft and acting between said driving member and an anchorage fixed to said shaft to bias said driving member axially in a direction opposite to the direction of axial movement of said driving member by said pin portion of said connecting means.

7. A starter according to claim 1, in which said driving member comprises a gear engageable with a larger gear of said engine when moved axially by said pin portion of said connecting member.

8. A starter according to claim 1, in which said means for rotating said shaft comprises a pulley fixed on said shaft and a cord wound on said pulley and extending out through an opening in said housing to be pulled to rotate the shaft in said first direction, and a rewind spring acting on said shaft to rotate it in the opposite direction to rewind said cord on said pulley.

9. A starter according to claim 8, in which said pulley has an axially projecting integral hub portion to which.

an inner end of said rewind spring is secured and on which said rewind spring is wound, an outer end of said rewind spring being secured to a portion of said housing.

10. A starter according to claim 9, in which said housing comprises a removable cover which encloses said rewind spring and retains said combined pulley and spring hub on said shaft.

11. A starter according to claim 1, comprising friction drag means for said driving member, comprising a friction disc movable axially with said driving member, means in said housing for restraining rotation of said disc while permitting its axial movement and friction means acting between said driving member and said disc to act as a drag on rotary movement of said driving means.

12. A starter according to claim 11, in which said disc is annular with at least one radially projecting finger for engagement with said housing to restrain rotary movement of said disc and in which said hub portion of the driving member has a radially extending flange capturing said disc between said flange and another portion of said driving member.

13. A starter according to claim 1, comprising means for mounting the starter on the side of an engine, comprising bands extending around said' housing and around anchorage portions provided on the engine, and

means for tensioning said bands. 

1. A starter for an internal combustion engine, comprising a housing, a shaft rotatable in the housing, means for rotating said shaft in a first direction to impart a starting movement to the engine, an engine driving member rotatable and axially slidable on said shaft and having a hub portion with a spiral slot opening onto one end face of the hub, a connecting member rotatable with and slidable axially of said shaft and having a projecting pin portion engaging in said spiral slot of said hub portion upon rotation of said shaft in said first direction to move said driving member axially into engagement with a driven means of said engine and thereupon to rotate said driving means in said first direction to impart a starting movement to the engine, said pin portion being engageable by said slot upon starting of the engine to drive said driving member faster than said shaft to move said connecting member axially to expel said pin portion from the open end of said slot and thereby disconnect said driving member from said shaft to permit overrun of said driving member, and means for biasing said connecting member axially in a direction opposite to said movement by overrun of said driving member.
 2. A starter according to claim 1, in which said shaft is hollow with an axially extending slot in a portion thereof, and in which said connecting member comprises a plunger slidable in said shaft and a radially projecting pin portion extends out through said axial slot in the shaft and into said spiral slot in the hub portion of said driving member.
 3. A starter according to claim 2, in which said hub pOrtion and said shaft have two symmetrically opposite slots and said plunger has a transverse pin extending out through the two opposite axial slots in the hollow shaft into the two opposite spiral slots in the hub portion of said driving member.
 4. A starter according to claim 3, in which said hollow shaft is symmetrical relative to a central transverse plane, with said opposite slots at one end to accommodate said pin and like opposite slots at the other end to accommodate means for connecting to said shaft said means for rotating the shaft.
 5. A starter according to claim 2, in which said biasing means comprises a coil spring in said hollow shaft acting between said plunger and an anchorage fixed to said shaft.
 6. A starter according to claim 5, further comprising a coil spring surrounding said shaft and acting between said driving member and an anchorage fixed to said shaft to bias said driving member axially in a direction opposite to the direction of axial movement of said driving member by said pin portion of said connecting means.
 7. A starter according to claim 1, in which said driving member comprises a gear engageable with a larger gear of said engine when moved axially by said pin portion of said connecting member.
 8. A starter according to claim 1, in which said means for rotating said shaft comprises a pulley fixed on said shaft and a cord wound on said pulley and extending out through an opening in said housing to be pulled to rotate the shaft in said first direction, and a rewind spring acting on said shaft to rotate it in the opposite direction to rewind said cord on said pulley.
 9. A starter according to claim 8, in which said pulley has an axially projecting integral hub portion to which an inner end of said rewind spring is secured and on which said rewind spring is wound, an outer end of said rewind spring being secured to a portion of said housing.
 10. A starter according to claim 9, in which said housing comprises a removable cover which encloses said rewind spring and retains said combined pulley and spring hub on said shaft.
 11. A starter according to claim 1, comprising friction drag means for said driving member, comprising a friction disc movable axially with said driving member, means in said housing for restraining rotation of said disc while permitting its axial movement and friction means acting between said driving member and said disc to act as a drag on rotary movement of said driving means.
 12. A starter according to claim 11, in which said disc is annular with at least one radially projecting finger for engagement with said housing to restrain rotary movement of said disc and in which said hub portion of the driving member has a radially extending flange capturing said disc between said flange and another portion of said driving member.
 13. A starter according to claim 1, comprising means for mounting the starter on the side of an engine, comprising bands extending around said housing and around anchorage portions provided on the engine, and means for tensioning said bands. 